Donald Davidson is perhaps the most distinguished philosopher in history never to have written a book. Indeed, he did not get round to writing articles until he was into his forties (he is now 76). Yet those articles – short, intense, allusive, hard – have changed the shape of contemporary analytical philosophy. They were in mid spate when I was a graduate student at Oxford in the early Seventies, and they acted as a kind of philosophical IQ test for the young philosophers of my generation. I well remember poring with tormented excitement over ‘Truth and Meaning’ and ‘Mental Events’, two of the most influential (and contested) articles of recent times. These cryptic texts gave the impression of well-honed conjuring tricks, in which the deepest of problems were given tantalisingly rigorous and ingenious solutions. In those days you were either a ‘Davidsonian’ or you weren’t; you certainly had to find out where you stood. But it wasn’t easy, because each Davidson article presupposed the others, and they assumed you were good at logic. It became clear that Davidson had a system, but it needed to be pieced together by the reader, as best he or she could. Puzzlement about a particular Davidson piece would be met with a knowing look from the initiated and the query ‘But have you read “In Defence of Convention T”?’ The very plainness of his name (often transmuted to David Donaldson) lent an aura of mystique to the plosive economy of the Davidson corpus. And the man himself, with his startling blue eyes and precisely articulated mode of speech, his unhurried confidence, his immersion in his own vision, his neatness, certainly encouraged the feeling that he had it all figured out, and all you had to do was figure him out. It did no harm, too, to discover that Davidson had been an enemy aircraft spotter in the US Navy in the Second World War, that he was a trained pilot, that he went gliding for a hobby, that he has climbed mountains, that there are very few places in the world he hasn’t visited. Davidson wasn’t just profound: he was cool (and there aren’t many philosophers you can say that about). Davidson had nerve.

The principal appeal of the Davidsonian system lies in its attempt to combine two conceptions of human beings that have traditionally been taken to be rivals. One conception, advocated by the positivists, though not unique to them, draws inspiration from the physical sciences and formal logic: it seeks to reduce mental discourse to physical discourse, and it offers to replace ordinary language with the kind of formalised language devised by Frege and his successors. Ultimately, there is nothing more to us than an arrangement of physical facts expressed in the notation of the predicate calculus. This conception effectively displaces our common-sense picture of mind and language in favour of a kind of pared-down physical naturalism in which we are represented as continuous with the rest of nature. The other conception, associated with the later Wittgenstein, but by no means unique to him, insists on the autonomy and legitimacy of our ordinary ways of thinking about human psychology and human language: these are not to be replaced by some austere physical theory or gleaming logical apparatus – for they are perfectly in order as they stand. We are, in fact, what we commonsensically take ourselves to be: rational agents with free choice. Man is not just an irregular clump of vibrating particles, nor need he be coached in the language of the logician: he has beliefs and desires and intentions, and his natural mode of expression is not to be improved on. He eludes physical science, at least in his mental and linguistic part: he is separate from the rest of nature and needs to be studied by methods peculiar to himself.

These two conceptions seem to represent radically incompatible ways of thinking of ourselves, and no middle ground appears to be available. But it is not as if either conception can be comfortably adopted to the exclusion of the other. The first view suffers from the problem that no such reduction or translation has ever been carried out, so that limiting ourselves to physical description will inevitably involve abandoning the idea that we have minds at all. Also, there seems to be a lot about natural language that cannot be reconstructed in terms of the usual logical systems, so that we would not be able to say as much if we spoke only Formalese. The price of seeing ourselves in these restricted ways is that what we see is no longer ourselves, but only some desiccated residue. On the other hand, if we remove the mind from the scientific domain completely, as the second view suggests, regarding ourselves as beyond the reach of causation, law and material composition, we run into equally severe problems. Do we not have brains that subserve our minds? Is not our behaviour somehow governed by natural law? Are we not in some clear sense ultimately made of matter? And is not formal logic an object of great beauty and power, giving undeniable insight into the structure of thought, whose services we should solicit and exploit? Hence the classic dilemma: how can we both be and not be an object of natural science?

Letters

Either Colin McGinn’s account (LRB, 19 August) of Donald Davidson’s theory of ‘anomalous monism’ is seriously deficient or Davidson’s theory is based on a misunderstanding of what it means to say that one thing is identical to another, a mistake that, perhaps, leads him to commit a gross logical blunder. As recounted by McGinn, Davidson’s ‘master stroke’ is to claim that 1. ‘every mental-event token is identical with some physical-event token in the brain;’ but 2. ‘mental-event types are not identical with physical-event types, nor are they reducible to them.’ The logical mistake is in asserting both 1. and 2. Whatever can be said of a particular thing can equally be said of any item identical to it. (A rose by any other name is still a rose.)

Take two of Smith’s mental-event tokens that are thoughts of milk. According to Davidson’s first claim, these mental-event tokens are identical with physical-event tokens in Smith’s brain. If this is so, then it follows by the logical principle of ‘identity substitution’ (Quinc calls it the ‘substitutivity of identity’) that if the Iwo mental-event tokens are of a given mental-event type, then so are the two corresponding physical-event tokens, because, in speaking of the mental-event tokens, one of necessity speaks of the corresponding physical-event tokens. (I cannot assert, say, that Sam Clemens was an interesting humorist without making the same claim about Mark Twain.) It also follows, of course, that if the mental-event tokens are identical with brain physical-event tokens, then those physical-event tokens are identical with the given mental-event tokens, and thus that if the former are of a given physical-event type, So are the latter, (I cannot assert that Mark Twain was an interesting humorist without making the same claim about Sam Clemens.) So Davidson’s theory of anomalous monism fails to get off the ground (not that much philosophical good would be done if it did, as critical remarks in McGinn’s article indicate).

Davidson’s theory cannot be saved by appealing to the fact that, to quote McGinn, ‘distinct particular dated events can fall under the same general description, and one and the same particular event can fall under many descriptions.’ It’s true that Smith’s two milk thoughts fall under the type thoughts-of-milk, as well as several other mental-event types, and that, for example, her thought of milk at time t1 falls under the types thoughts-of-milk, Smith’s-thoughts and thoughts-at time tl, as well as others. But if Smith’s thoughts of milk are identical with brain physical events, then those physical events also fall under the type thoughts-of-milk etc, and her brain physical event at time t1 under thoughts of milk, Smith’s thoughts, thoughts-at-time-t1 etc. Similarly, Smith’s two thoughts of milk will exemplify many physical-event types.

Note also that the theory of anomalous monism cannot be saved by way of the speculation that mental events identical except with respect to space and time, let’s call them quasi-identical, may each be identical with physical events that differ in other ways – for instance, as to which sorts of brain neurons fire. Consider, for example, the idea that two quasi-identical thoughts Smith has of milk, one at t1 and the other at t2, might be identical with brain physical-events that are not quasi-identical to each other. A Davidson devotee might argue that in such a case, the mental-event type to which only the two quasi-identical milk thoughts belong would not be identical with any physical-event type of which only the two relevant physical events are members, thus giving the theory of anomalous monism some running room.

The trouble, as before, is that this sort of reasoning fails to take account of what it means for items to be identical (let’s not worry about quasi-identity). If the two quasi-identical mental events fall under a given type, then, since they are by hypothesis identical to the two non-quasi-identical physical events, so do these physical events. This is, of course, another way of saying that if the two mental-events are not even quasi-identical, then, on pain of logical contradiction, the said mental events cannot be identical to the said physical events. Anyone who accepts Davidson’s theory identifying mental events with brain physical events must reject his idea that ‘no systematic relation between mental and physical discourse is entailed by this identity of events’, for mental discourse will be physical discourse, and certain physical discourse will be mental discourse. (Mark Twain discourse is Sam Clemens discourse.) Identicals are identical.

It’s interesting to note that confusion as to the nature of identity and/or the principle of identity substitution is by no means restricted to the case at hand. A similar mistake is made, for example, by those who argue that the principle of identity substitution often fails in so called indirect, or intentional, contexts, as though that sort of failure has to do with some special feature of the identity substitution principle (or of the alleged intentional contexts?) rather than with plain old equivocation. Every valid inference rule, after all, is larded with the proviso that its use has to be restricted to unequivocal uses of language. But I digress.

Howard Kahane (Letters, 7 October) has, I am afraid, wasted your column inches broadcasting his own confusions and misunderstandings. He announces that Davidson’s anomalous monism violates Leibniz’s law of the indiscernibility of identicals, so that the position is logically contradictory. Pause for a moment to reflect that if this were so the entire philosophical community would have failed for over twenty years to notice a whopping logical error in token identity theories that deny type identity. Then observe that it is Mr Kahane himself who is the logical myope: yes, it does follow from the identity of two mental tokens of type M with two physical tokens that those physical tokens are also of type M; but (I say wearily) it does not follow, by Leibniz’s law or anything else, that those two physical tokens are of the same physical type. Compare: if two red objects are identical with two objects that have shape, then those shaped objects indeed have the same colour; but it does not (of course) follow that they have the same shape. So neither Davidson nor I has forgotten that what you can say of something you can say of anything identical to it.

Colin McGinn’s reply (Letters, 21 October 1993) to my claim that his account of Donald Davidson’s theory of anomalous monism is contradictory contains at least three ad hominems, an appeal to the authority of others who have agreed with him over the past twenty years, and (wearily, he says) exactly one reason for supposing he is right, namely a comparison that, by itself, does not prove his case.

My claim was that, as described by Mr McGinn, the two key theses of Davidson’s theory (‘every mental-event token is identical with some physical-event token in the brain,’ and ‘mental-event types are not identical with physical-event types, nor are they reducible to them’) are contradictory. Whether I am right or not on this, it now seems to me, depends on just what McGinn/Davidson mean by the claim that ‘every mental-event token is identical with some physical-event token in the brain.’ I took this statement to assert what it seems to say, namely that every mental event, literally, is identical with some physical event, not that some events have two different kinds of properties, one kind being mental, the other physical. In other words, I took him to be describing a neural identity theory – a theory that claims consciousness literally is a brain process – not a kind of neutral monism according to which some events have two different sorts of properties, one kind mental, the other physical.

Suppose, then, that I am right as to what sort of theory McGinn was telling us about. Then clearly, McGinn’s comparison – ‘if two red objects are identical with two objects that have shape, then those shaped objects indeed have the same colour; but it does not (of course) follow that they have the same shape’ – is beside the point. The red colour token of a red and, say, square object clearly is not identical with that object’s square shape; but if all mental events are literally identical with physical events, then a particular, say, milk thought has to be literally identical with some physical event or other. So on this construal, McGinn’s comparison misses the mark. (Many philosophers, including this one, have wondered how someone can believe that two so different sorts of things as a thought and a neural firing are literally identical, but that is another matter.)

I must confess, however, that nothing McGinn said in his description of Davidson’s theory absolutely rules out the possibility that he had in mind a neutral monistic theory that somehow puts together into one event two different, non-identical items, one mental and the other physical, just as the objects in McGinn’s comparison put together a red patch and a square shape. If that is what he meant to say, then I have to retract my claim as to the contradictory nature of McGinn’s account of Davidson’s theory, and have to agree that McGinn’s comparison is indeed apt. In that case, though, there is very little ‘cash value’ difference between Davidson’s theory and certain kinds of dualistic theories, including some that postulate uncaused, ‘free’ wills as a way to solve the free will problem Davidson’s theory is designed to solve. (Note, by the way, that McGinn’s article on Davidson neglects even to mention compatibilism, the position championed by Hobbes and Hume, and perhaps the solution to the problem of free will versus determinism most widely held in the English-speaking philosophical world.) It also seems to me rather odd, not to mention misleading, to say that a milk thought token is identical with a brain firing token when what is meant is that they are different, non-identical, properties of the same event, just as it would be odd and misleading to say that the red of an object is identical with that object’s weight when what is meant is that they are two different properties of the same object.

In any case, motivated by McGinn’s article and letter, I turned to the relevant Davidson article, ‘Mental Events’, in an attempt to figure out what Davidson had in mind, but have to confess my inability to come to a firm decision as to precisely what he was up to. Consider, for example, that his criterion for mental-eventhood makes virtually every physical event also into a mental event, including, and this is Davidson’s own example, the ‘collision of two stars in distant space’. It counts as a mental event, says Davidson, if that event happens to be ‘simultaneous with Jones’s noticing that a pencil starts to roll across his desk’ – the point being, I have to assume, since he doesn’t say, that we can then describe the star collision by the definite description ‘the star collision simultaneous with Jones’s noticing the start of a pencil rolling across his desk’, a description that for him is mental because of the mental verb ‘noticing’.